Embodiments relate to a light emitting device, a light emitting device package, and a lighting system.
In light emitting devices, P-N junction diodes having the properties of converting electrical energy into light energy may be formed by combining group III and V elements on the periodic table. Light emitting devices may implement various colors by controlling the composition ratio of compound semiconductors.
In light emitting devices, when a forward voltage is applied, an electron of an n-layer is combined with a hole of a p-layer to emit energy corresponding to an energy gap between the conduction band and the valance band. The energy is generally emitted in the form of heat or light. In light emitting devices, the energy is emitted in the form of light.
Nitride semiconductors, for example, are attracting much attention for the fields of optical devices and high-power electronic devices because of their high thermal stability and wide band gap energy. In particular, blue light emitting devices, green light emitting devices, and UV light emitting devices that use nitride semiconductors have been commercialized and are widely used.
For example, to form a white light emitting device package, light emitting devices of red, green and blue, which are the three primary colors of light, may be combined, or a yellow phosphor such as yttrium aluminum garnet (YAG) and terbium aluminum garnet (TAG) may be added to a blue light emitting device, or a (red/green/blue) three-colored phosphor may be used in a UV light emitting device.
However, in a related art white light emitting device package including a phosphor, the phosphor may be unevenly distributed around a chip of a light emitting device, and thus, a wide color temperature distribution may be formed.
In addition, since a distribution area of a phosphor is greater than the area of a light emitting device, the phosphor may be unevenly distributed around a chip of the light emitting device, and thus, a wide color temperature distribution may be also formed.